1. Field of the Invention
The present invention relates to an inkjet printer.
2. Description of the Related Art
Conventionally, an inkjet printer is known including a recording head injecting ink that is cured when being irradiated with ultraviolet rays (hereinafter, referred to as “ultraviolet-curable ink”) toward a recording medium such as a recording paper sheet or the like and an ultraviolet irradiation device irradiating the ultraviolet-curable ink injected onto the recording medium with ultraviolet rays (e.g., Japanese Laid-Open Patent Publication No. 2011-93179 and Japanese Patent No. 4457622).
Also known is an inkjet printer 100 shown in FIG. 8 including a first recording head 141, a second recording head 142, a first ultraviolet irradiation device 151, and a second ultraviolet irradiation device 152. In the inkjet printer 100, the recording medium is located below the first recording head 141 and the second recording head 142. The first recording head 141 and the second recording head 142 inject ultraviolet-curable ink toward the recording medium while moving in a direction, of a main scanning direction Y, from one side to the other side (hereinafter, such a direction will be referred to as a “forward direction Y1”) and a direction, of the main scanning direction Y, from the other side to the one side (hereinafter, such a direction will be referred to as a “backward direction Y2”). The second recording head 142 is provided on the one side of the main scanning direction Y with respect to the first recording head 141. The first ultraviolet irradiation device 151 is provided on the other side of the main scanning direction Y with respect to the first recording head 141. The second ultraviolet irradiation device 152 is provided on the one side of the main scanning direction Y with respect to the second recording head 142. The ultraviolet-curable ink injected by the first recording head 141 and the second recording head 142 while the first recording head 141 and the second recording head 142 are moving in the forward direction Y1 is cured by ultraviolet rays provided by the second ultraviolet irradiation device 152. In contrast, the ultraviolet-curable ink injected by the first recording head 141 and the second recording head 142 while the first recording head 141 and the second recording head 142 are moving in the backward direction Y2 is cured by ultraviolet rays provided by the first ultraviolet irradiation device 151.
In the inkjet printer 100, distance D101 in the main scanning direction Y between middle position L101 in the main scanning direction Y of the first recording head 141 and middle position L103 in the main scanning direction Y of the first ultraviolet irradiation device 151, and distance D102 in the main scanning direction Y between middle position L101 of the first recording head 141 and middle position L104 in the main scanning direction Y of the second ultraviolet irradiation device 152, are different from each other. Similarly, distance D103 in the main scanning direction Y between middle position L102 in the main scanning direction Y of the second recording head 142 and middle position L103 of the first ultraviolet irradiation device 151, and distance D104 in the main scanning direction Y between middle position L102 of the second recording head 142 and middle position L104 of the second ultraviolet irradiation device 152, are different from each other. Therefore, for example, the time until the ultraviolet ink injected onto the recording medium from the first recording head 141 moving in the forward direction Y1 is cured, and the time until the ultraviolet ink injected onto the recording medium from the first recording head 141 moving in the backward direction Y2 is cured, are different from each other. As the time until the ultraviolet ink is cured is longer, a dot of the ultraviolet ink has a longer diameter. Therefore, in this case, the ink dots of the ultraviolet ink injected onto the recording medium may be different in accordance with whether the ink is injected in the forward direction Y1 or the backward direction Y2. This may result in printing unevenness caused as a result of printing.